Magnetoresistive structures, semiconductor devices, and related systems

ABSTRACT

Magnetic memory cells, methods of fabrication, semiconductor device structures, and memory systems are disclosed. A magnetic cell core includes at least one magnetic region (e.g., a free region or a fixed region) configured to exhibit a vertical magnetic orientation, at least one oxide-based region, which may be a tunnel junction region or an oxide capping region, and at least one magnetic interface region, which may comprise or consist of iron (Fe). In some embodiments, the magnetic interface region is spaced from at least one oxide-based region by a magnetic region. The presence of the magnetic interface region enhances the perpendicular magnetic anisotropy (PMA) strength of the magnetic cell core. In some embodiments, the PMA strength may be enhanced more than 50% compared to that of the same magnetic cell core structure lacking the magnetic interface region.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/194,875, filed Jun. 28, 2016, pending, which is a divisional of U.S.patent application Ser. No. 13/797,185, filed Mar. 12, 2013, now U.S.Pat. No. 9,379,315, issued Jun. 28, 2016, the disclosure of each ofwhich is hereby incorporated in its entirety herein by this reference.

TECHNICAL FIELD

The present disclosure, in various embodiments, relates generally to thefield of memory device design and fabrication. More particularly, thisdisclosure relates to design and fabrication of memory cellscharacterized as spin torque transfer magnetic random access memory(STT-MRAM) cells.

BACKGROUND

Magnetic Random Access Memory (MRAM) is a non-volatile computer memorytechnology based on magnetoresistance. One type of MRAM cell is a spintorque transfer MRAM (STT-MRAM) cell, which includes a magnetic cellcore supported by a substrate. The magnetic cell core includes at leasttwo magnetic regions, for example, a “fixed region” and a “free region,”with a non-magnetic region in-between. The fixed region includes amagnetic material that has a fixed (e.g., a non-switchable) magneticorientation, while the free region includes a magnetic material that hasa magnetic orientation that may be switched, during operation of thecell, between a “parallel” configuration, in which the magneticorientation of the fixed region and the magnetic orientation of the freeregion are directed in the same direction (e.g., north and north, eastand east, south and south, or west and west, respectively), and an“anti-parallel” configuration, in which the magnetic orientation of thefixed region and the magnetic orientation of the free region aredirected in opposite directions (e.g., north and south, east and west,south and north, or west and east, respectively).

In the parallel configuration the STT-MRAM cell exhibits a lowerelectrical resistance across the magnetoresistive elements, i.e., thefixed region and free region. This state of relatively low electricalresistance may be defined as a “0” state of the MRAM cell. In theanti-parallel configuration, the STT-MRAM cell exhibits a higherelectrical resistance across the magnetoresistive elements, i.e., theregions of magnetic material, e.g., the fixed region and free region.This state of relatively high electrical resistance may be defined as a“1” state of the MRAM cell. Switching of the magnetic orientation of thefree region and the resulting high or low resistance states across themagnetoresistive elements enables the write and read operations of theconventional MRAM cell. Ideally, the amount of programming currentrequired to switch the free region from the parallel configuration tothe anti-parallel configuration is essentially the same amount ofprogramming current required to switch from the anti-parallelconfiguration to the parallel configuration. Such equal programmingcurrent for switching is referred to herein as “symmetric switching.”

The free regions and fixed regions of STT-MRAM cells may exhibitmagnetic orientations that are either horizontally oriented (“in-plane”)or perpendicularly oriented (“out-of-plane”) with the width of theregions. In STT-MRAM cells that have perpendicularly-oriented magneticregions, the magnetic materials exhibiting the vertical magneticorientation may be characterized by a strength of the magneticmaterials' perpendicular magnetic anisotropy (“PMA”). The strength (alsoreferred to herein as the “magnetic strength” or the “PMA strength”) isan indication of the magnetic materials' resistance to alteration of themagnetic orientation. A magnetic material exhibiting a vertical magneticorientation with a high PMA strength may be less prone to alteration ofits magnetic orientation out of the vertical orientation than a magneticmaterial exhibiting a vertical magnetic orientation with a lowermagnetic strength. However, achieving a high PMA strength may not besufficient, in and of itself, for successful STT-MRAM cell operation.For example, a low resistance-area (RA), a low switching current, a lowswitching voltage, and symmetric switching may also contribute tosuccessful operation of an STT-MRAM cell. However, finding materials anddesigns in which a high PMA strength is exhibited without adverselyaffecting the other characteristics of the STT-MRAM cell's operation,particularly the RA of the cell, may present a challenge.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional, elevational, schematic illustration of amagnetic cell core of an STT-MRAM cell including a magnetic interfaceregion disposed directly between a free region and a magnetic tunneljunction region.

FIG. 2 is a cross-sectional, elevational, schematic illustration of amagnetic cell core of an STT-MRAM cell including a magnetic interfaceregion disposed directly between a free region and an oxide cap region.

FIG. 3 is a cross-sectional, elevational, schematic illustration of amagnetic cell core of an STT-MRAM cell including a magnetic interfaceregion disposed directly between a magnetic sub-region of a free regionand an oxide cap region.

FIG. 4 is a cross-sectional, elevational, schematic illustration of amagnetic cell core of an STT-MRAM cell including a magnetic interfaceregion disposed within a free region.

FIG. 5 is a cross-sectional, elevational, schematic illustration of amagnetic cell core of an STT-MRAM cell including two magnetic interfaceregions, one of which being disposed directly between a free region andan oxide cap region and another being disposed directly between the freeregion and a magnetic tunnel junction region.

FIG. 6 is a cross-sectional, elevational, schematic illustration of amagnetic cell core of an STT-MRAM cell including four magnetic interfaceregions, of which one pair is disposed on top and on bottom of a freeregion and another pair is disposed on top and on bottom of a fixedregion.

FIG. 7 is a cross-sectional, elevational, schematic illustration of amagnetic cell core of an STT-MRAM cell including one magnetic interfaceregion within a free region and another magnetic interface region on topof a fixed region.

FIG. 8 is a schematic diagram of an STT-MRAM system having a memory cellaccording to an embodiment of the present disclosure.

FIG. 9 is a simplified block diagram of a semiconductor device structureincluding memory cells of an embodiment of the present disclosure.

FIG. 10 is a simplified block diagram of a system implemented accordingto one or more embodiments of the present disclosure.

FIG. 11 is a graph displaying measurements of PMA strength for amagnetic cell core incorporating a magnetic interface region incomparison with a magnetic cell core lacking the magnetic interfaceregion.

DETAILED DESCRIPTION

Memory cells, semiconductor device structures including such memorycells, memory systems, and methods of forming such memory cells aredisclosed. The memory cells include a magnetic region, such as a freeregion or a fixed region, exhibiting a vertical magnetic orientation.The memory cells also include at least one oxide region, such one ormore of an oxide-based magnetic tunnel junction (“MTJ”) region and anoxide capping region. Disposed, directly or indirectly, between themagnetic region and the oxide region is a magnetic interface region thatis configured to increase the PMA strength of the memory cell, comparedto memory cells lacking the magnetic interface region, but withoutsignificantly adversely affecting other characteristics of the memorycell, such as the resistance-area of the memory cell. For example, a lowRA (e.g., less than about 20 Ω·μm² (Ohms×microns squared)) may bemaintained even with enhanced PMA strength (e.g., a uniaxial anisotropyfield (H_(k)) exceeding about 4,000 Oe (Oersted)). Accordingly, themagnetic interface region may enhance operational performance of themagnetic region (e.g., the free region or the fixed region) within amagnetic memory cell structure that accommodates high data retentiontime and low power operation.

As used herein, the term “substrate” means and includes a base materialor other construction upon which components, such as those within memorycells, are formed. The substrate may be a semiconductor substrate, abase semiconductor material on a supporting structure, a metalelectrode, or a semiconductor substrate having one or more materials,structures, or regions formed thereon. The substrate may be aconventional silicon substrate or other bulk substrate including asemiconductive material. As used herein, the term “bulk substrate” meansand includes not only silicon wafers, but also silicon-on-insulator(“SOI”) substrates, such as silicon-on-sapphire (“SOS”) substrates orsilicon-on-glass (“SOG”) substrates, epitaxial layers of silicon on abase semiconductor foundation, or other semiconductor or optoelectronicmaterials, such as silicon-germanium (Si_(1-x)Ge_(x), where x is, forexample, a mole fraction between 0.2 and 0.8), germanium (Ge), galliumarsenide (GaAs), gallium nitride (GaN), or indium phosphide (InP), amongothers. Furthermore, when reference is made to a “substrate” in thefollowing description, previous process stages may have been utilized toform materials, regions, or junctions in the base semiconductorstructure or foundation.

As used herein, the term “STT-MRAM cell” means and includes a magneticcell structure that includes a non-magnetic region disposed between afree region and a fixed region. The non-magnetic region may be anelectrically insulative (e.g., dielectric) region, in a magnetic tunneljunction (“MTJ”) configuration. Alternatively, the non-magnetic regionmay be an electrically conductive region, in a spin-valve configuration.

As used herein, the term “cell core” means and includes a memory cellstructure comprising the free region and fixed region and through which,during use and operation of the memory cell, current flows to effect aparallel or anti-parallel magnetic orientation within the free region.

As used herein, the term “vertical” means and includes a direction thatis perpendicular to the width and length of the respective region.“Vertical” may also mean and include a direction that is perpendicularto a primary surface of the substrate on which the STT-MRAM cell islocated.

As used herein, the term “horizontal” means and includes a directionthat is parallel to at least one of the width and length of therespective region. “Horizontal” may also mean and include a directionthat is parallel to a primary surface of the substrate on which theSTT-MRAM cell is located.

As used herein, the term “magnetic material” means and includesferromagnetic materials, ferrimagnetic materials, and antiferromagneticmaterials.

As used herein, the term “iron-based material” means and includes amaterial that includes iron. For example, and without limitation,iron-based materials include pure iron, an iron alloy, and materialsincluding cobalt and iron. The composition of the iron-based materialmay be altered due to annealing of the iron-based material duringfabrication of the magnetic memory cell, but such material may,nonetheless, be referred to herein as an “iron-based material.”

As used herein, the term “magnetic region” means a region that exhibitsmagnetism. A magnetic region includes a magnetic material and may alsoinclude one or more non-magnetic materials.

As used herein, the term “sub-region,” means and includes a regionincluded in another region. Thus, one magnetic region may include one ormore magnetic sub-regions, i.e., sub-regions of magnetic material, aswell as non-magnetic sub-regions, i.e., sub-regions of non-magneticmaterial.

As used herein, the term “fixed region” means and includes a magneticregion within the STT-MRAM cell that includes magnetic material and thathas a fixed magnetic orientation during use and operation of theSTT-MRAM cell in that a current or applied field effecting a change inthe magnetization direction of one magnetic region, e.g., the freeregion, of the cell core may not effect a change in the magnetizationdirection of the fixed region. The fixed region may include one or moremagnetic materials and, optionally, one or more non-magnetic materials.For example, the fixed region may be configured as a syntheticantiferromagnet (SAF) including a sub-region of ruthenium (Ru) adjoinedby magnetic sub-regions. Each of the magnetic sub-regions may includeone or more materials and one or more regions therein. As anotherexample, the fixed region may be configured as a single, homogenousmagnetic material. Accordingly, the fixed region may have uniformmagnetization or sub-regions of differing magnetization that, overall,effect the fixed region having a fixed magnetic orientation during useand operation of the STT-MRAM cell.

As used herein, the term “free region” means and includes a magneticregion within the STT-MRAM cell that includes magnetic material and thathas a switchable magnetic orientation during use and operation of theSTT-MRAM cell. The magnetic orientation may be switched between a“parallel” direction, in which the magnetic orientation exhibited by thefree region and the magnetic orientation exhibited by the fixed regionare oriented in the same direction, and an “anti-parallel” direction, inwhich the magnetic orientation exhibited by the free region and themagnetic orientation exhibited by the fixed region are oriented inopposite directions from one another.

As used herein, the term “oxide region” means and includes a regionwithin the STT-MRAM cell that includes an oxide material. For example,and without limitation, an oxide region may include an oxide-based MTJregion, an oxide capping region, or both.

As used herein, the term “between” is a spatially relative term used todescribe the relative disposition of one material, region, or sub-regionrelative to at least two other materials, regions, or sub-regions. Theterm “between” can encompass both a disposition of one material, region,or sub-region directly adjacent to the other materials, regions, orsub-regions and a disposition of one material, region, or sub-region notdirectly adjacent to the other materials, regions, or sub-regions.

As used herein, reference to an element as being “on” or “over” anotherelement means and includes the element being directly on top of,adjacent to, underneath, or in direct contact with the other element. Italso includes the element being indirectly on top of, adjacent to,underneath, or near the other element, with other elements presenttherebetween. In contrast, when an element is referred to as being“directly on” or “directly adjacent to” another element, there are nointervening elements present.

As used herein, other spatially relative terms, such as “beneath,”“below,” “lower,” “bottom,” “above,” “upper,” “top,” “front,” “rear,”“left,” “right,” and the like, may be used for ease of description todescribe one element's or feature's relationship to another element(s)or feature(s) as illustrated in the figures. Unless otherwise specified,the spatially relative terms are intended to encompass differentorientations of the materials in addition to the orientation as depictedin the figures. For example, if materials in the figures are inverted,elements described as “below” or “beneath” or “under” or “on bottom of”other elements or features would then be oriented “above” or “on top of”the other elements or features. Thus, the term “below” can encompassboth an orientation of above and below, depending on the context inwhich the term is used, which will be evident to one of ordinary skillin the art. The materials may be otherwise oriented (rotated 90 degrees,inverted, etc.) and the spatially relative descriptors used hereininterpreted accordingly.

As used herein, the terms “comprises,” “comprising,” “includes,” and/or“including” specify the presence of stated features, regions, integers,stages, operations, elements, materials, components, and/or groups, butdo not preclude the presence or addition of one or more other features,regions, integers, stages, operations, elements, materials, components,and/or groups thereof.

As used herein, “and/or” includes any and all combinations of one ormore of the associated listed items.

As used herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise.

The illustrations presented herein are not meant to be actual views ofany particular component, structure, device, or system, but are merelyidealized representations that are employed to describe embodiments ofthe present disclosure.

Embodiments are described herein with reference to cross-sectionalillustrations that are schematic illustrations. Accordingly, variationsfrom the shapes of the illustrations as a result, for example, ofmanufacturing techniques and/or tolerances, are to be expected. Thus,embodiments described herein are not to be construed as limited to theparticular shapes or regions as illustrated, but include deviations inshapes that result, for example, from manufacturing. For example, aregion illustrated or described as box-shaped may have rough and/ornonlinear features. Moreover, sharp angles that are illustrated may berounded. Thus, the materials, features, and regions illustrated in thefigures are schematic in nature, and their shapes are not intended toillustrate the precise shape of a material, feature, or region and donot limit the scope of the present claims.

The following description provides specific details, such as materialtypes and processing conditions, in order to provide a thoroughdescription of embodiments of the disclosed devices and methods.However, a person of ordinary skill in the art will understand that theembodiments of the devices and methods may be practiced withoutemploying these specific details. Indeed, the embodiments of the devicesand methods may be practiced in conjunction with conventionalsemiconductor fabrication techniques employed in the industry.

The fabrication processes described herein do not form a completeprocess flow for processing semiconductor device structures. Theremainder of the process flow is known to those of ordinary skill in theart. Accordingly, only the methods and semiconductor device structuresnecessary to understand embodiments of the present devices and methodsare described herein.

Unless the context indicates otherwise, the materials described hereinmay be formed by any suitable technique including, but not limited to,spin coating, blanket coating, chemical vapor deposition (“CVD”), atomiclayer deposition (“ALD”), plasma enhanced ALD, or physical vapordeposition (“PVD”). Alternatively, the materials may be grown in situ.Depending on the specific material to be formed, the technique fordepositing or growing the material may be selected by a person ofordinary skill in the art.

Unless the context indicates otherwise, the removal of materialsdescribed herein may be accomplished by any suitable techniqueincluding, but not limited to, etching, ion milling, abrasiveplanarization, or other known methods.

Reference will now be made to the drawings, where like numerals refer tolike components throughout. The drawings are not necessarily drawn toscale.

A memory cell is disclosed. The memory cell includes at least onemagnetic region (e.g., a free region or a fixed region) exhibiting avertical magnetic orientation and an oxide region (e.g., an MTJ regionor an oxide capping region) with a magnetic interface region disposed,directly or indirectly, therebetween. The magnetic interface region mayenhance the PMA strength of the magnetic memory cell. The magneticinterface region may be disposed adjacent to or within its respectivemagnetic region. In some embodiments, the memory cell may include onlyone magnetic interface region; however, in other embodiments, more thanone magnetic interface region may be included in the memory cell.

FIG. 1 illustrates a magnetic cell core 100 of an STT-MRAM cellaccording to an embodiment of the present disclosure. The magnetic cellcore 100 is supported by a substrate 102. The magnetic cell core 100includes at least two magnetic regions, for example, a “fixed region”110 and a “free region” 120 with a nonmagnetic region 130 in between.One or more lower intermediary regions 140 and one or more upperintermediary regions 150 may, optionally, be disposed under and over,respectively, the magnetic regions (e.g., the fixed region 110 and thefree region 120) of the magnetic cell core 100 structure.

In some embodiments, as illustrated in FIG. 1, the magnetic cell core100 may include an optional conductive material forming a seed region160 on the substrate 102. The seed region 160, if present, or the lowerintermediary regions 140, if the seed region 160 is not present, may beformed over a bottom conductive material (not shown), which may include,for example and without limitation, copper, tungsten, titanium, or acombination thereof. The seed region 160, if present, may include, forexample and without limitation, a nickel-based material and may beconfigured to control the crystal structure of an overlying material orregion. The lower intermediary regions 140, if present, may includematerials configured to ensure a desired crystal structure of overlyingmaterials in the magnetic cell core 100.

The STT-MRAM cell may be configured to exhibit a vertical magneticorientation in at least one of the magnetic regions (e.g., the fixedregion 110 and the free region 120). The vertical magnetic orientationexhibited may be characterized by the perpendicular magnetic anisotropy(“PMA”) strength. As illustrated in FIG. 1 by arrows 112 and 122, insome embodiments, each of the fixed region 110 and the free region 120may exhibit a vertical magnetic orientation. The magnetic orientation ofthe fixed region 110 may remain directed in essentially the samedirection throughout operation of the STT-MRAM cell, for example, in thedirection indicated by arrows 112 of FIG. 1. The magnetic orientation ofthe free region 120, on the other hand, may be switched, duringoperation of the cell, between a “parallel” configuration and an“anti-parallel” configuration, as indicated by double-pointed arrows 122of FIG. 1. In the parallel orientation, the magnetic orientation 122 ofthe free region 120 is directed in essentially the same direction (e.g.,north) as the magnetic orientation 112 of the fixed region 110 (e.g.,north), producing a lower electrical resistance across themagnetoresistive elements, i.e., the fixed region 110 and the freeregion 120, in what may be defined as the “0” state of the STT-MRAMcell. In the anti-parallel configuration, the magnetic orientation 122of the free region 120 is directed essentially in the opposite direction(e.g., south) of the magnetic orientation 112 of the fixed region 110(e.g. north), producing a higher electrical resistance across themagnetoresistive elements, i.e., the fixed region 110 and the freeregion 120, in what may be defined as the “1” state of the STT-MRAMcell.

In use and operation, a programming current may be caused to flowthrough an access transistor (not shown) and the magnetic cell core 100.The fixed region 110 within the magnetic cell core 100 polarizes theelectron spin of the programming current. The spin-polarized electroncurrent interacts with the free region 120 by exerting a torque on thefree region 120. When the torque of the spin-polarized electron currentpassing through the free region 120 is greater than a critical switchingcurrent density (J_(c)) of the free region 120, the torque exerted bythe spin-polarized electron current is sufficient to switch thedirection of the magnetization of the free region 120, e.g., between anorth-directed magnetic orientation and a south-directed magneticorientation. Thus, the programming current can be used to cause themagnetic orientation 122 of the free region 120 to be aligned eitherparallel to or anti-parallel to the magnetic orientation 112 of thefixed region 110.

The free region 120 and the fixed region 110 may be formed from orcomprise ferromagnetic materials, such as Co, Fe, Ni, or their alloys,NiFe, CoFe, CoNiFe, or doped alloys CoX, CoFeX, CoNiFeX (X=B, Cu, Re,Ru, Rh, Hf, Pd, Pt, C), or other half-metallic ferromagnetic materials,such as, for example, NiMnSb and PtMnSb. In some embodiments, forexample, the free region 120, the fixed region 110, or both may beformed from Co_(x)Fe_(y)B_(z), wherein x=10 to 80, y=10 to 80, and z=0to 50. In other embodiments, the free region 120, the fixed region 110,or both may be formed of iron (Fe) and boron (B) and not include cobalt(Co). The compositions and structures (e.g., the thicknesses and otherphysical dimensions) of the free region 120 and the fixed region 110 maybe the same or different.

Alternatively or additionally, in some embodiments, the free region 120,the fixed region 110, or both, may be formed from or comprise aplurality of materials, some of which may be magnetic materials and someof which may be nonmagnetic materials. For example, some suchmulti-material free regions, fixed regions, or both, may includemultiple sub-regions. For example, and without limitation, the freeregion 120, the fixed region 110, or both, may be formed from orcomprise repeating sub-regions of cobalt and platinum, wherein asub-region of platinum may be disposed between sub-regions of cobalt. Asanother example, without limitation, the free region 120, the fixedregion 110, or both, may comprise repeating sub-regions of cobalt andnickel, wherein a sub-region of nickel may be disposed betweensub-regions of cobalt.

The nonmagnetic region 130, disposed between the fixed region 110 andthe free region 120, may include nonmagnetic materials (such as anonmagnetic oxide material, e.g., magnesium oxide (MgO), aluminum oxide(Al₂O₃), titanium oxide (TiO₂), or other oxide materials of conventionalMTJ regions). Accordingly, such oxide-including MTJ region may bereferred to herein as an “oxide-based MTJ region” or an “oxide-basednonmagnetic region.” The nonmagnetic region 130 may include one or moresuch nonmagnetic materials. Alternatively or additionally, thenonmagnetic region 130 may include sub-regions of one or morenonmagnetic materials.

As illustrated in FIG. 1, the magnetic cell core 100 may, in someembodiments, include an oxide capping region 170, which may includeoxides such as MgO, TiO₂, tantalum pentoxide (Ta₂O₅), or combinationsthereof. Accordingly, such oxide-including capping region may bereferred to herein, also, as an “oxide-based nonmagnetic region.” Insome embodiments, the oxide capping region 170 may include the samematerials, structure, or both of the nonmagnetic region 130. Forexample, the oxide capping region 170 and the nonmagnetic region 130 mayboth include a magnesium oxide (e.g., MgO), an aluminum oxide, atitanium oxide, a zinc oxide, hafnium oxide, a ruthenium oxide, or atantalum oxide.

The optional upper intermediary regions 150, if present, may includematerials configured to ensure a desired crystal structure inneighboring materials of the magnetic cell core 100. The upperintermediary regions 150 may alternatively or additionally include metalmaterials configured to aid in patterning processes during fabricationof the magnetic cell core 100, barrier materials, or other materials ofconventional STT-MRAM cell core structures. In some embodiments, such asthat illustrated in FIG. 1, the upper intermediary regions 150 mayinclude a conductive capping region, which may include one or morematerials such as copper, tantalum, titanium, tungsten, ruthenium,tantalum nitride, or titanium nitride.

The magnetic cell core 100, according to the present disclosure, alsoincludes a magnetic interface region 180 disposed between one of themagnetic regions or magnetic sub-regions (e.g., the fixed region 110, amagnetic sub-region of the fixed region 110, the free region 120, or amagnetic sub-region of the free region 120) and one of the oxide regions(e.g., the nonmagnetic region 130 and the oxide capping region 170). Asillustrated in FIG. 1, the magnetic interface region 180 may be disposeddirectly adjacent to one of the magnetic regions or magnetic sub-regionsand one of the oxide regions. According to the embodiment illustrated inFIG. 1, the magnetic interface region 180 may be disposed directly ontop of the nonmagnetic region 130 and directly beneath the free region120. As situated, the magnetic interface region 180 may be disposedbetween two oxide regions, i.e., between an oxide-based MTJ (e.g., thenonmagnetic region 130) and the oxide capping region 170.

The magnetic interface region 180 may be configured to enhance the PMAstrength of the magnetic cell core 100, or, more particularly, of itsneighboring magnetic region, e.g., the free region 120 according to theembodiment illustrated in FIG. 1. The increased PMA may be achievedwhile maintaining a low resistance-area (e.g., less than about 20 Ω·μm²(Ohms×microns squared)) of the magnetic cell core 100. The magneticinterface region 180 may be formed of a magnetic material, such as aniron-based material, e.g., iron (Fe) alone, an iron alloy, or, in someembodiments, a cobalt-iron (CoFe) based material.

The material of the magnetic interface region 180 may be in the form ofa monolayer of iron or other iron-including compound disposed betweenthe nonmagnetic region 130 and the oxide capping region 170.Alternatively or additionally, the magnetic interface region 180 mayhave a thickness (i.e., a height along an axis perpendicular to an uppersurface of the substrate 102) that is less than about 10 Å (e.g., lessthan about 5 Å, e.g., about 3 Å). As such, the magnetic interface region180 may be thinner than its neighboring regions. For example, theoverlying free region 120 of FIG. 1 may be formed to have a thickness ofabout 15 Å to about 30 Å, and the underlying nonmagnetic region 130 ofFIG. 1 may be formed to have a thickness of about 7 Å to about 10 Å.

The magnetic interface region 180 may be formed from a materialformulated or otherwise configured to have the same crystal orientationas that of the material upon which it is formed. For example, accordingto the embodiment illustrated in FIG. 1, the magnetic interface region180 may be formed from iron (Fe) in such a manner (e.g., by magnetronsputtering) as to have the same crystal orientation as MgO within thenonmagnetic region 130.

The magnetic interface region 180 may be formed by, e.g., magnetronsputtering. For example, the materials of the lower regions of themagnetic cell core 100 may be formed successively, such as in layers,following which the magnetic material of the magnetic interface region180 may be formed over the previously-formed materials. The materials ofthe upper regions of the magnetic cell core 100 may then be formedsuccessively, such as in layers, above the magnetic material of themagnetic interface region 180. Accordingly, the material of the magneticinterface region 180 may be formed so as to be disposed between twooxide-based materials, i.e., the oxide materials from which thenonmagnetic region 130 and the oxide capping region 170 are to beformed.

Following formation of the materials of the magnetic cell core 100, thematerials may be patterned to form the magnetic cell core 100 comprisingthe various regions thereof. Techniques for forming and patterning thematerials of the lower and upper regions of the magnetic cell core 100are known in the art and, therefore, are not described in detail herein.For example, the magnetic cell core 100 may be formed by forming each ofthe materials of the regions thereof in sequential order, from base totop, and then patterning the materials to define the magnetic cell core100. The magnetic cell core 100 structure may be annealed at atemperature of at least 150° C. (e.g., between about 150° C. and about400° C.) before or after patterning. Alternatively or additionally,materials of the magnetic cell core 100 structure may be annealed duringfabrication of the magnetic cell core 100 structure, e.g., afterformation of one or more materials of the magnetic cell core 100structure and before other materials thereof are formed.

In embodiments such as that illustrated in FIG. 1, in which the magneticinterface region 180 is disposed directly between the nonmagnetic region130 and the free region 120, and in which the magnetic interface region180 is disposed between the nonmagnetic region 130 and the oxide cappingregion 170, it is contemplated that, without being bound to any oneparticular theory, the magnetic interface region 180 enables iron-oxygenbonding between iron in the magnetic interface region 180 and oxygen inthe oxide material of the neighboring oxide-based region, e.g., thenonmagnetic region 130. Iron-oxygen bonding may contribute tointerfacial PMA strength. It is contemplated that the contribution tointerfacial PMA strength by iron-oxygen bonding may be greater than acontribution from other oxygen bonding, such as cobalt-oxygen bonding.Accordingly, the inclusion of the magnetic interface region 180 in themagnetic cell core 100 may enable a stronger PMA than that achieved by amagnetic cell core structure lacking a magnetic interface region 180between a magnetic region such as the free region 120 and an oxideregion such as the nonmagnetic region 130.

Accordingly, disclosed is a memory cell comprising a magnetic cell coreon a substrate. The magnetic cell core comprises a magnetic regionbetween an oxide region and another oxide region. The magnetic regionexhibits a vertical magnetic orientation. A magnetic interface region isdisposed between the oxide region and the another oxide region.

With reference to FIG. 2, illustrated is a magnetic cell core 200 inwhich the magnetic interface region 180 is disposed between thenonmagnetic region 130 and the oxide capping region 170, but above thefree region 120. Thus, the nonmagnetic region 130 is disposed to oneside of, e.g., underneath, the free region 120 while the magneticinterface region 180 is disposed to another side of, e.g., above, thefree region 120. The materials of the magnetic cell core 200 may be thesame as those of the magnetic cell core 100 (FIG. 1) described above.The magnetic cell core 200 may be formed by forming each of thematerials of the regions thereof in sequential order, from base to top,and then patterning the materials to define the magnetic cell core 200structure. Thus, the magnetic interface region 180 may be formeddirectly on the free region 120, and the oxide capping region 170 may beformed directly on the magnetic interface region 180. In otherembodiments (not shown in FIG. 2), the positions of the free region 120and the fixed region 110 may be interchanged such that the magneticinterface region 180 would be disposed between the oxide capping region170 and the fixed region 110, which would be positioned above thenonmagnetic region 130.

Accordingly, disclosed is a method of forming a memory cell, the methodcomprising forming an oxide material over a substrate. A magneticmaterial is formed over the oxide material. Another oxide material isformed over the magnetic material. An iron-based material is formedbetween the magnetic material and one of the oxide material and theanother oxide material. The oxide material, the magnetic material, theanother oxide material, and the iron-based material are patterned toform a magnetic cell core comprising a tunnel junction region from theoxide material, one of a free region and a fixed region from themagnetic material, a magnetic interface region from the iron-basedmaterial, and an oxide capping region from the another oxide material.The magnetic material exhibits a vertical magnetic orientation.

With reference to FIG. 3, in some embodiments, a magnetic cell core 300according to the present disclosure may include magnetic regions, suchas the free region, the fixed region, or both, having a multi-materialstructure. For example, the fixed region 110 of the embodiment of FIG.3, or any of the preceding or following described embodiments, may beconfigured as an SAF with a Ru sub-region neighbored on top and bottomby a magnetic sub-region. As another example, as illustrated, themagnetic cell core 300 may include a multi-material free region 320. Themulti-material free region 320 may include an upper magnetic sub-region324 spaced from (i.e., not directly in physical contact with) a lowermagnetic sub-region 326 by a spacer 328. In other embodiments, themulti-material free region 320 may lack the spacer 328. In still otherembodiments, the multi-material free region 320 may have more than twomagnetic sub-regions, more than one spacer 328, or both.

The material or materials from which the upper magnetic sub-region 324and the lower magnetic sub-region 326 are formed may be the samematerial or materials, respectively, from which the free region 120 maybe formed, as described above. For example, and without limitation, eachof the upper magnetic sub-region 324 and the lower magnetic sub-region326 may be formed from Co_(x)Fe_(y)B_(z), wherein x=1, y=50 to 60, andz=1 to 30, e.g., CoFe₅₀B₃₀. As another example, the upper magneticsub-region 324 may be formed of CoFeB₆₀ while the lower magneticsub-region 326 may be formed of CoFe₅₀B₃₀.

Each of the upper magnetic sub-region 324 and the lower magneticsub-region 326 may be formed to each be thicker than the spacer 328. Insome embodiments, the lower magnetic sub-region 326 may have a thicknessof about 10 Å, and the upper magnetic sub-region 324 may have athickness of about 6 Å. In other embodiments, the upper magneticsub-region 324 and the lower magnetic sub-region 326 may be formed tohave approximately equal thicknesses, e.g., from about 6 Å to about 10Å.

The spacer 328 may be formed from a conductive material such as, forexample and without limitation, tantalum (Ta). The spacer 328 may berelatively thin compared to the overlying and underlying sub-regions.For example, the spacer 328 may have a thickness of less than about 3 Å,e.g., about 1.5 Å.

The multi-material free region 320 may be formed by forming each of thematerials thereof sequentially, from base to top, before the materialsare patterned to form the magnetic cell core 300.

According to the embodiment of FIG. 3, the magnetic interface region 180may be formed over the multi-material free region 320, so as to bedisposed between the nonmagnetic region 130 and the oxide capping region170. Thus, the magnetic interface region 180 may be directly between theupper magnetic sub-region 324 and the oxide capping region 170.

Accordingly, disclosed is a memory cell comprising a magnetic cell corecomprising a free region configured to exhibit a switchable verticalmagnetic orientation and a fixed region configured to exhibit a fixedvertical magnetic orientation. A nonmagnetic region is disposed betweenthe free region and the fixed region. A magnetic interface region isspaced from the nonmagnetic region by one of the free region and thefixed region.

With reference to FIG. 4, a magnetic cell core 400, according to thepresent disclosure, having a multi-material free region 420 comprisingthe upper magnetic sub-region 324, the lower magnetic sub-region 326,and the spacer 328, may be structured to also comprise the magneticinterface region 180. That is, the magnetic interface region 180 may bedisposed directly adjacent to, either above or below, the spacer 328 andone of the upper magnetic sub-region 324 and the lower magneticsub-region 326. In this structure, the magnetic interface region 180 isspaced from both of the oxide-based regions, i.e., the nonmagneticregion 130 and the oxide capping region 170. Nonetheless, the presenceof the magnetic interface region 180 may enhance the PMA strength of atleast the magnetic region incorporating the magnetic interface region180, which, as illustrated in in FIG. 4, may be the free region (e.g.,the multi-material free region 420). For example, the PMA strength ofthe magnetic region (e.g., the multi-material free region 420) may begreater than about 4,000 Oersted (e.g., greater than about 5,000Oersted).

In a structure such as that of the magnetic cell core 400 of FIG. 4, theupper magnetic sub-region 324 and the lower magnetic sub-region 326 maybe of the same thicknesses. Alternatively, the total thickness of themagnetic interface region 180 and the one of the upper magneticsub-region 324 and the lower magnetic sub-region 326 to which themagnetic interface region 180 is adjacent may be about equal to thethickness of the other of the upper magnetic sub-region 324 and thelower magnetic sub-region 326. For example, the lower magneticsub-region 326 may have a thickness of about 10 Å, while the uppermagnetic sub-region 324 may have a thickness of about 6 Å and themagnetic interface region 180 may have a thickness of about 4 Å.

The materials of the multi-material free region 420 may be formedsequentially, from base to top, whereby the magnetic interface region180 may be formed directly on the spacer 328, and the upper magneticsub-region 324 may be formed directly on the magnetic interface region180.

With reference to FIG. 5, a magnetic cell core 500 according to thepresent disclosure may, alternatively, include more than one magneticinterface region 180. For example, as illustrated in FIG. 5, a pair ofmagnetic interface regions 180 may be disposed such that one overliesone of the magnetic regions of the magnetic cell core 500, e.g.,overlies the free region 120, while another magnetic interface region180 of the pair underlies the same magnetic region, e.g., underlies thefree region 120. Again, the materials of the magnetic cell core 500 maybe formed sequentially, from base to top, and may be patterned to formthe magnetic cell core 500.

With reference to FIG. 6, in some embodiments a magnetic cell core 600may include more than two magnetic interface regions 180, such as onemagnetic interface region 180 directly on each of the top and bottom ofeach of the magnetic regions (e.g., the free region 120 and the fixedregion 110) of the magnetic cell core 600. Again, the materials of themagnetic cell core 600 may be formed sequentially, from base to top, andmay be thereafter patterned to form the magnetic cell core 600.

With reference to FIG. 7, it is contemplated that one of the magneticregions of a magnetic cell core 700, such as the free region or, forexample, a multi-material free region 720 may incorporate the magneticinterface region 180 while another magnetic region of the magnetic cellcore 700, such as the fixed region 110 may be adjacent to anothermagnetic interface region 180. Again, the materials of such magneticcell core 700 may be formed sequentially, from base to top.

Accordingly, the number of magnetic interface regions 180 and thedisposition of such magnetic interface regions 180 may be tailoredaccording to the desired STT-MRAM structure and operability. Likewise,the exact composition and thickness of the magnetic interface region 180may be tailored to achieve a desired PMA strength, which may be thehighest PMA strength (e.g., H_(k) (Oe)) achievable without adverselyimpacting the operation of the STT-MRAM cell. It is contemplated thatthe thickness of the magnetic interface region 180 may be optimized,through testing, to be of a thickness great enough to enhance the PMAstrength while less than the thickness that would negatively impact theoperation characteristics of the STT-MRAM cell.

In embodiments in which multiple magnetic interface regions 180 areincluded in the magnetic cell core (e.g., magnetic cell cores 500, 600,or 700), the magnetic interface regions 180 within the magnetic cellcores 500, 600, or 700 may have equal thicknesses or, alternatively, thethicknesses of the magnetic interface regions 180 may vary from oneanother. Again, it is contemplated that the relative thicknesses of themultiple magnetic interface regions 180 may be optimized, throughtesting.

Following formation of the magnetic cell core (e.g., one of magneticcell cores 100-700), the semiconductor device structure may be subjectedto additional fabrication steps, as known in the art, to form anoperational semiconductor device, such as an STT-MRAM cell, an array ofSTT-MRAM cells, an STT-MRAM system, a processor-based system, or anycombination thereof.

With reference to FIG. 8, illustrated is an STT-MRAM system 800 thatincludes peripheral devices 812 in operable communication with anSTT-MRAM cell 814, a plurality of which may be fabricated to form anarray of memory cells in a grid pattern including a number of rows andcolumns, or in various other arrangements, depending on the systemrequirements and fabrication technology. The STT-MRAM cell 814 includesa cell core 802, an access transistor 803, a conductive material thatmay function as a data/sense line 804 (e.g., a bit line), a conductivematerial that may function as an access line 805 (e.g., a word line),and a conductive material that may function as a source line 806. Theperipheral devices 812 of the STT-MRAM system 800 may include read/writecircuitry 807, a bit line reference 808, and a sense amplifier 809. Thecell core 802 may be any one of the magnetic cell cores 100-700described above. Due to the structure of the cell core 802, i.e., theinclusion of the magnetic interface region 180 (FIGS. 1-7) that isspaced from the nonmagnetic region 130, e.g., the tunnel region or MTJ,or from the oxide capping region 170 and the resultant enhancement ofthe PMA strength of the STT-MRAM cell 814, the STT-MRAM cell 814 mayexhibit a higher data retention time and operate effectively at lowerpower than a conventional STT-MRAM cell.

In use and operation, when an STT-MRAM cell 814 is selected to beprogrammed, a programming current is applied to the STT-MRAM cell 814,and the current is spin-polarized by the fixed region of the cell core802 and exerts a torque on the free region of the cell core 802, whichswitches the magnetization of the free region to “write to” or “program”the STT-MRAM cell 814. In a read operation of the STT-MRAM cell 814, acurrent is used to detect the resistance state of the cell core 802.

To initiate programming of the STT-MRAM cell 814, the read/writecircuitry 807 may generate a write current to the data/sense line 804and the source line 806. The polarity of the voltage between thedata/sense line 804 and the source line 806 determines the switch inmagnetic orientation of the free region in the cell core 802. Bychanging the magnetic orientation of the free region with the spinpolarity, the free region is magnetized according to the spin polarityof the programming current, the programmed state is written to theSTT-MRAM cell 814.

To read the STT-MRAM cell 814, the read/write circuitry 807 generates aread voltage to the data/sense line 804 and the source line 806 throughthe cell core 802 and the access transistor 803. The programmed state ofthe STT-MRAM cell 814 relates to the resistance across the cell core802, which may be determined by the voltage difference between thedata/sense line 804 and the source line 806. In some embodiments, thevoltage difference may be compared to the bit line reference 808 andamplified by the sense amplifier 809.

FIG. 8 illustrates one example of an operable STT-MRAM system 800. It iscontemplated, however, that the magnetic cell cores 100-700 (FIGS. 1-7)may be incorporated and utilized within any STT-MRAM system configuredto incorporate a magnetic cell core having magnetic regions exhibitingvertical magnetic orientations. Notably, because the thickness of themagnetic interface region 180 (FIGS. 1-7) may be relatively thin,relative to other regions of the magnetic cell cores 100-700, the totalheight of the magnetic cell cores 100-700 may be the same or not muchgreater than the height of a conventional magnetic cell core of anSTT-MRAM cell. Further, because the magnetic interface region 180 may beformed using techniques the same as or similar to techniques used toform other regions of the magnetic cell cores 100-700, the overallfabrication process may not be significantly altered to accomplishformation of the magnetic cell cores 100-700 in accordance withembodiments of the present disclosure.

Accordingly, disclosed is a spin torque transfer magnetic random accessmemory (STT-MRAM) system comprising a magnetic cell core comprising amagnetic interface region on or in a magnetic region. The magneticregion is configured to exhibit a vertical magnetic orientation. Anoxide region is spaced from the magnetic interface region. The STT-MRAMsystem also comprises a plurality of conductive materials in operablecommunication with the magnetic cell core.

With reference to FIG. 9, illustrated is a simplified block diagram of asemiconductor device structure 900 implemented according to one or moreembodiments described herein. The semiconductor device structure 900includes a memory array 902 and a control logic component 904. Thememory array 902 may include a plurality of the STT-MRAM cells 814 (FIG.8) including any of the magnetic cell cores 100-700 (FIGS. 1-7)discussed above, which magnetic cell cores 100-700 (FIGS. 1-7) may havebeen formed according to a method described above. The control logiccomponent 904 may be configured to operatively interact with the memoryarray 902 so as to read from or write to any or all memory cells (e.g.,STT-MRAM cell 814) within the memory array 902.

Accordingly, disclosed is a semiconductor device structure comprising aspin torque transfer magnetic random access memory (STT-MRAM) arraycomprising a plurality of STT-MRAM cells. Each STT-MRAM cell of theplurality comprises a cell core comprising a nonmagnetic region betweena magnetic region and another magnetic region. Each of the magneticregion and the another magnetic region are configured to exhibit avertical magnetic orientation. An oxide region is spaced from thenonmagnetic region by one of the magnetic region and the anothermagnetic region. A magnetic interface region is disposed between theoxide region and the nonmagnetic region.

With reference to FIG. 10, depicted is a processor-based system 1000.The processor-based system 1000 may include various electronic devicesmanufactured in accordance with embodiments of the present disclosure.The processor-based system 1000 may be any of a variety of types such asa computer, pager, cellular phone, personal organizer, control circuit,or other electronic device. The processor-based system 1000 may includeone or more processors 1002, such as a microprocessor, to control theprocessing of system functions and requests in the processor-basedsystem 1000. The processor 1002 and other subcomponents of theprocessor-based system 1000 may include magnetic memory devicesmanufactured in accordance with embodiments of the present disclosure.

The processor-based system 1000 may include a power supply 1004. Forexample, if the processor-based system 1000 is a portable system, thepower supply 1004 may include one or more of a fuel cell, a powerscavenging device, permanent batteries, replaceable batteries, andrechargeable batteries. The power supply 1004 may also include an ACadapter; therefore, the processor-based system 1000 may be plugged intoa wall outlet, for example. The power supply 1004 may also include a DCadapter such that the processor-based system 1000 may be plugged into avehicle cigarette lighter or a vehicle power port, for example.

Various other devices may be coupled to the processor 1002 depending onthe functions that the processor-based system 1000 performs. Forexample, a user interface 1006 may be coupled to the processor 1002. Theuser interface 1006 may include input devices such as buttons, switches,a keyboard, a light pen, a mouse, a digitizer and stylus, a touchscreen, a voice recognition system, a microphone, or a combinationthereof. A display 1008 may also be coupled to the processor 1002. Thedisplay 1008 may include an LCD display, an SED display, a CRT display,a DLP display, a plasma display, an OLED display, an LED display, athree-dimensional projection, an audio display, or a combinationthereof. Furthermore, an RF sub-system/baseband processor 1010 may alsobe coupled to the processor 1002. The RF sub-system/baseband processor1010 may include an antenna that is coupled to an RF receiver and to anRF transmitter (not shown). A communication port 1012, or more than onecommunication port 1012, may also be coupled to the processor 1002. Thecommunication port 1012 may be adapted to be coupled to one or moreperipheral devices 1014, such as a modem, a printer, a computer, ascanner, or a camera, or to a network, such as a local area network,remote area network, intranet, or the Internet, for example.

The processor 1002 may control the processor-based system 1000 byimplementing software programs stored in the memory. The softwareprograms may include an operating system, database software, draftingsoftware, word processing software, media editing software, or mediaplaying software, for example. The memory is operably coupled to theprocessor 1002 to store and facilitate execution of various programs.For example, the processor 1002 may be coupled to system memory 1016,which may include one or more of spin torque transfer magnetic randomaccess memory (STT-MRAM), magnetic random access memory (MRAM), dynamicrandom access memory (DRAM), static random access memory (SRAM),racetrack memory, and other known memory types. The system memory 1016may include volatile memory, non-volatile memory, or a combinationthereof. The system memory 1016 is typically large so that it can storedynamically loaded applications and data. In some embodiments, thesystem memory 1016 may include semiconductor device structures, such asthe semiconductor device structure 900 of FIG. 9, memory cells includingany of magnetic cell cores 100-700 (FIG. 1-7), or a combination thereof.

The processor 1002 may also be coupled to non-volatile memory 1018,which is not to suggest that system memory 1016 is necessarily volatile.The non-volatile memory 1018 may include one or more of STT-MRAM, MRAM,read-only memory (ROM) such as an EPROM, resistive read-only memory(RROM), and Flash memory to be used in conjunction with the systemmemory 1016. The size of the non-volatile memory 1018 is typicallyselected to be just large enough to store any necessary operatingsystem, application programs, and fixed data. Additionally, thenon-volatile memory 1018 may include a high capacity memory such as diskdrive memory, such as a hybrid-drive including resistive memory or othertypes of non-volatile solid-state memory, for example. The non-volatilememory 1018 may include semiconductor device structures, such as thesemiconductor device structure 900 of FIG. 9, memory cells including anyof magnetic cell 100-700 (FIGS. 1-7), or a combination thereof.

The following example is presented to illustrate an embodiment of thepresent disclosure in more detail. This example is not to be construedas being exhaustive or exclusive as to the scope of this disclosure.

EXAMPLE

A partial magnetic cell core structure, without a magnetic contributionfrom a fixed region, was fabricated to evaluate the PMA strength of afree region fabricated according to an embodiment of the presentdisclosure. The partial magnetic cell core structure included aconductive seed region having a thickness of about 50 Å; an overlyingdummy fixed region of CoFeB having a thickness of about 5 Å; anoverlying nonmagnetic region of MgO having a thickness of about 12 Å; anoverlying multi-material free region comprising a lower magneticsub-region of CoFeB having a thickness of about 10 Å, an overlyingspacer of Ta having a thickness of about 1.5 Å, and an overlying uppermagnetic sub-region of CoFeB, with slightly different B concentrationthan the lower magnetic sub-region, having a thickness of about 6 Å; anoverlying magnetic interface region of Fe having a thickness of about 4Å; an overlying oxide capping region of MgO having a thickness of about7 Å; and an overlying upper conductive capping region having a thicknessof about 500 Å. This partial magnetic cell core structure exhibited aPMA strength (measured by H_(k) (Oe)) of 5,007 Oe, as indicated by dataline 1200 of FIG. 11. This compares to a PMA strength of 2,992 Oe, asindicated by data line 1100 of FIG. 11, exhibited by the same structurelacking the magnetic interface region of Fe. Accordingly, the magneticcell core structure with the magnetic interface region disposed over thefree region, adjacent to the oxide capping region, exhibited a more than50% increase in PMA strength compared to the same structure without themagnetic interface region.

While the present disclosure is susceptible to various modifications andalternative forms in implementation thereof, specific embodiments havebeen shown by way of example in the drawings and have been described indetail herein. However, the present disclosure is not intended to belimited to the particular forms disclosed. Rather, the presentdisclosure encompasses all modifications, combinations, equivalents,variations, and alternatives falling within the scope of the presentdisclosure as defined by the following appended claims and their legalequivalents.

1. A magnetoresistive structure, comprising: a free region configured toexhibit a switchable vertical magnetic orientation; a fixed regionconfigured to exhibit a fixed vertical magnetic orientation; anonmagnetic region between the free region and the fixed region; and amagnetic interface region spaced from the nonmagnetic region by one ofthe free region and the fixed region.
 2. The magnetoresistive structureof claim 1, wherein the magnetic interface region comprises one ofcobalt-iron and cobalt.
 3. The magnetoresistive structure of claim 1,wherein the magnetic interface region has a thickness less than about 10Å.
 4. The magnetoresistive structure of claim 1, wherein the magneticinterface region is located directly between the nonmagnetic region andthe free region.
 5. The magnetoresistive structure of claim 1, whereinthe magnetic interface region is located between the free region and acapping region.
 6. The magnetoresistive structure of claim 1, whereinthe magnetic interface region is disposed within the free region.
 7. Themagnetoresistive structure of claim 1, further comprising anothermagnetic interface region disposed on a side of the free region.
 8. Themagnetoresistive structure of claim 7, wherein the free region isdisposed between the another magnetic interface region and the magneticinterface region.
 9. The magnetoresistive structure of claim 1, furthercomprising another magnetic interface region proximate the fixed region.10. A semiconductor device, comprising: a free region exhibiting aswitchable magnetic orientation, the free region between an oxide regionand another oxide region; a fixed region exhibiting a fixed magneticvertical orientation on a side of the oxide region; a magnetic interfaceregion between the oxide region and the another oxide region, themagnetic interface region having a thickness less than about 10 Å. 11.The semiconductor device of claim 10, wherein the magnetic interfaceregion directly contacts each of the oxide region and the free region.12. The semiconductor device of claim 10, wherein the magnetic interfaceregion consists of iron.
 13. The semiconductor device of claim 10,wherein the oxide region comprises an oxide of magnesium, aluminum, ortitanium.
 14. The semiconductor device of claim 10, further comprisinganother magnetic interface region contacting at least one of the freeregion and the fixed region.
 15. The semiconductor device of claim 10,wherein the free region comprises iron and at least one of cobalt andboron.
 16. The semiconductor device of claim 10, wherein an interfacebetween the magnetic interface region and free region comprises ironfrom the magnetic interface region bonded to oxygen from the oxideregion.
 17. A system, comprising: at least one magnetoresistivestructure, the at least one magnetoresistive structure comprising: afree region configured to exhibit a switchable vertical magneticorientation; an oxide region over the free region; a fixed regionconfigured to exhibit a fixed vertical magnetic orientation over theoxide region; and a magnetic interface region spaced from the oxideregion by one of the free region and the fixed region; and a processorcoupled to the at least one magnetoresistive structure.
 18. The systemof claim 17, wherein the magnetic interface region consists of iron. 19.The system of claim 17, wherein the magnetic interface region has athickness less than about 10 Å.
 20. The system of claim 17, furthercomprising another magnetic interface region in contact with at leastone of the free region and the fixed region.